1. Field of the Invention
This invention relates to a picture taking apparatus, such as cameras, having a focusing device, and more particularly, to digital cameras.
2. Description of the Related Art
A digital camera has image pickup means for electrically detecting an image of a subject through a photographing lens. It is widely known that digital cameras perform focusing using an image signal outputted from the image pickup means. This auto focus technology finely adjusts the focus of the photographing lens to find a lens position where the contrast of an image becomes highest. Accordingly, with digital cameras, time to move the photographing lens is needed and this so-called release time lag may become long. This type of focusing technology in which the photographing lens is controlled to move it toward a position where the contrast of an image becomes highest is called a hill-climbing auto-focusing method.
Numerous auto-focusing (AF) methods for correctly focusing a subject regardless of its location in a picture have been proposed recently. These methods are known as a multi-focus system. Displaying a focusing result in a viewfinder is described in, for example, Laid-Open Japanese Patent Application No. Hei 10-48,733.
Hei 10-48,733 discloses a camera capable of selecting, automatically or by a manual manipulation of a photographer, any of three distance measuring points provided in a picture for photography and focusing a subject existing at the selected distance measuring point. However, the control sequence of this camera is set so that if a previously selected distance measuring point needs to be changed, the control sequence returns to a distance measuring point selecting step after the previously selected distance measuring point has already been focused. Consequently, repeating focusing takes time and delays photography. This delay may become unacceptable particularly if the hill-climbing auto-focusing method is used.